I. Field of the Invention
The present invention relates to a rotary knob for an electrical system, comprising a body on which can be mounted a rotary maneuvering member, in particular a hand grip or a rotor controlled by a key, and of housing a driving part for switching contacts.
II. Description of Related Art
In conventional rotary knobs, the maneuvering member is provided with a shank for moving the driving part, and the body also serves as a support for at least one electrical contact block, switchable in response to the rotation of the maneuvering member via at least one axially moving slider. The maneuvering member is mounted on the body such that it rotates about an axis with a limited angular movement, in order to assume at least two functional positions, maintained or transitory. Rotary knobs of this type are well known (see for example the documents DE 34 12 518 and DE 35 41 390). The maneuvering member is locked in rotation with a driving part having a cam able to actuate the slider or sliders and the body is able to receive the hand grip in a fluid-tight manner, to serve as a support for the electrical blocks and to house the driving part and the sliders.
These knobs sometimes have the disadvantage that, although the maneuvering member is placed in one of its functional positions, a slight force applied to that member can suffice to make a notch of the cam jump and to drive the knob in an inopportune manner.